Tag Archives: Chips

Why shaving dulls even the sharpest of blades

Shaving technology has progressed quite a bit in the past few decades, but one thing has remained annoyingly constant over time: the fact that blades get dull with use.

Image credits: Hamid Roshaan.

Human hair is 50 times softer than the blade itself — so it doesn’t seem like it would be too much of a challenge to cut through. At first, it’s not. New blades (at least the quality ones) get the job done easily. But if you use them again (and again and again), they tend to get dull.

Many shaving razors (especially the small ones) also can’t be sharpened. Knives, for comparison, can be sharpened and last for many years, but blades need to be replaced quickly. To see why this happens, a team of MIT engineers looked at this interaction in unprecedented detail.

“Our main goal was to understand a problem that more or less everyone is aware of: why blades become useless when they interact with much softer material,” says C. Cem Tasan, the Thomas B. King Associate Professor of Metallurgy at MIT. “We found the main ingredients of failure, which enabled us to determine a new processing path to make blades that can last longer.”

Tasan is a specialist. His work focuses on exploring the microstructure of metals and see what can be changed to make them more resilient in time.

“We are metallurgists and want to learn what governs the deformation of metals, so that we can make better metals,” Tasan says. “In this case, it was intriguing that, if you cut something very soft, like human hair, with something very hard, like steel, the hard material would fail.”

He found that when it comes to shaving blades, the blade doesn’t technically get dull. Whether it’s single-blade, multi-blade, or safety razors, the blade is still sharp. What happens is that it tends to develop tiny chips. If you’ve ever shaved with a blade that had chips, the odds are you would have felt it pinching at some of your hairs. But researchers weren’t exactly sure why this happened.

To make matters even more puzzling, the chips were showing up in the same places on different blades.

“This created another mystery: We saw chipping, but didn’t see chipping everywhere, only in certain locations,” Tasan says. “And we wanted to understand, under what conditions does this chipping take place, and what are the ingredients of failure?”

To solve the puzzle, Gianluca Roscioli, lead author and MIT graduate student, set up a system to carry out controlled shaving experiments. The device consisted of a movable stage with two clamps: one that held the razor blade and the other that anchored the strands of hair. They then shaved strands of hair of different thicknesses and held at various angles, observing the process with an electron microscope. Roscioli used his own hair, as well as hair sampled from several of his labmates, to ensure that he was representing a wide range of hair diameters. The process looked like this:

The team observed the same thing, regardless of the hair thickness: hair caused the blade’s edge to chip, but only in certain spots. Then, after the first chip forms, cracks accumulate around it, and further chipping quickly appears.

But they also started to see other patterns. For instance, chips didn’t seem to occur when the hair was perpendicular to the blade. But when the razor could shift and bend, chips were more likely to occur, especially on the edge of the blade. The team carried out computer simulations which predicted that failure is dependent on the angle. The models showed that the composition of the blade’s steel was also important, with heterogeneous blades more likely to chip.

The mechanism producing the chips is called stress intensification. When you shave, some stress is applied to the blade — and if there are microcracks or inhomogeneities, it’s more likely to crack.

“Our simulations explain how heterogeneity in a material can increase the stress on that material, so that a crack can grow, even though the stress is imposed by a soft material like hair,” Tasan says.

So if you want your blade to last longer, reduce its heterogeneity while maintaining its hardness — and if possible, try to shave perpendicular to the strands of hair.

The study was published in Science.

NASA creates computers that can survive on Venus, 30 years after the last landings

NASA’s Glenn Research Center has developed a new class of computers that can withstand the hellscape of Venus. The devices are built from a different semiconductor than regular hardware, which can carry more voltage at much higher temperatures.

SiC transistor gate electroluminesces blue while cooked at more than 400°C.
Image credits NASA / Glenn RC.

Mars has been getting a lot of attention as humanity’s first planned colony. So it’s easy to forget that it’s neither the closest nor the most Earth-like terrestrial planet in the Solar System. Both those distinctions belong to Venus — so why aren’t we looking towards it for our otherworldly adventures?

The goddess of love and beauty

Well, the thing is that Venus is awful. It’s an objectively dreadful place, a scorching hot ball of rock covered in thick clouds of boiling acid. Ironic, right?

These conditions not only make it nigh-impossible for real-estate agents to put a positive spin on the planet, it also makes it frustratingly hard to explore. Any mission to Venus has to work around one simple fact: your run of the mill computer wouldn’t like it there. Normal silicone chips can still function up to 240-250°C (482°F). After that, the chip turns from a semiconductor into a fully fledged conductor, electrons start jumping all over the place, and the system crashes.

The longest any human-made object has made it on Venus is 127 minutes, a record set in 1981 by the Soviet spacecraft Venera 13. It was designed to survive for only 32 minutes and used all kinds of tricks to make that happen — such as cooling of internal systems to -10°C (14°F) before entering the atmosphere, hermetically sealed internal chambers for instruments, and so on. Venera braved sulphuric rain, surface temperatures of 470°C (878°F), and an atmosphere 90 times that of Earth long enough to capture the first color pictures of the planet’s surface.

The face of love.
Image credits Morbx / Reddit.

After the mission, the Soviets flew three more crafts to Venus — Venera 14, Vega 1, and Vega 2 — making the last attempted landing on the planet in 1985.

Since that time, the transistor industry has developed alternative materials it can use for integrated systems. One of the most promising class of materials are silicon carbides (SiC). Their ability to support high voltages at huge temperatures has already drawn interest from the military and heavy industries, and make them ideal for a mission to Venus.

NASA’s Glenn Research Center has developed two prototype SiC chips which can be used in future Venus missions. The researchers have also worked to overcome another vulnerability of traditional integrated circuits: they’ve developed interconnects — the wires that tie transistors to other hardware components — which can withstand the extreme conditions on the planet.

Five hundred hours of fire

SiC chip designed by NASA, before and after GEER tests.
Image credits NASA / Glenn RC.

To see if the technology lives up to expectations, the team put these SiC transistors and interconnects together and housed them in ceramic-packed chips. The chips were then placed in the GEER (Glenn Extreme Environments Rig) which can simulate the temperatures and pressures on Venus for hundreds of hours at a time.

One of the chips, housing a simple 3-stage oscillator, kept stable at 1.26MHz over 521 hours (over 21 days) before the GEER had to be shut down. The second chip fizzled out after 109 hours (4,5 days), but NASA determined that it was caused by faulty setup, not the chip itself.

The results for the two chips. Image credits NASA / Glenn RC.

This performance is a far cry from that seen in the 80’s, especially considering that the chips didn’t benefit from any pressure vessels, cooling systems, or other types of protection. It’s the first system shown able to withstand the condition on Venus for weeks at a time.

“With further technology maturation, such SiC IC electronics could drastically improve Venus lander designs and mission concepts, fundamentally enabling long-duration enhanced missions to the surface of Venus,” the researchers conclude.

But it’s not only transistors we’ll need for a successful Venus rover. Drills, cameras, wheels — everything has to be adapted to work in a high pressure, high temperature, highly acidic environment. Materials science has evolved a long way since the last missions, so creating a mechanically-sound lander should be feasible. A full-fledged rover with multiple moving parts that can survive on Venus would be a lot harder to develop — NASA Glenn is working on such a machine, a land-sailing rover, which they estimate will be ready by 2033.

The full paper “Prolonged silicon carbide integrated circuit operation in Venus surface atmospheric conditions” has been published in the journal AIP Advances.

Scientists develop memory chips from egg shells

Eggshells might become the data storage of the future. A Chinese team showed that the material can be used to create greener RAM storage for out computers.

Image credits Steve Buissinne / Pixabay.

You’ve heard of eggplants, but what about eggcomputers? Seeking to bring the term about, a team from the Guizhou Institute of Technology hatched a cunning plan: they went to the market, bought a few random eggs, and ground their shells for three hours to make a homogeneous, nano-sized powder. After it was dry, the team mixed this powder into a solution and poured it onto a substrate.

They thus ended up with the part of a memory chip through which electricity actually flows — the electrolyte. But eggshells are not an item you tend to see in chip factories, so how could it function as RAM? Well, the team tested the egg-paste to see if it changes its electrical resistance when a voltage flows through it. This property can be used to create memory chips of the ReRAM, or resistive random access memory, variety. There’s a lot of interest in ReRAMas it could be used to create faster, denser, and more energy efficient storage media than traditional RAM or flash memory.

And it worked. The team was able to encode 100 bits of binary information into the eggmemory before it failed. It doesn’t stack up to the billions of cycles regular materials can take, but as a proof of concept it’s incredible.

It’s ground eggshell. That can store binary data.

Still, we’re a long way off from seeing one of these devices on the market. But if they do show promise for future applications and, with enough developement, could provide a clean, sustainable, and very egg-y alternative to the electrolytes in use today.

The full paper “A larger nonvolatile bipolar resistive switching memory behaviour fabricated using eggshells” have been published in the journal Current Applied Physics.